Optimized thermocouple system and method

ABSTRACT

An optimized thermocouple system and a method of optimizing a thermocouple system having a plurality of thermocouple probes and a junction box is provided and includes examining the thermocouple system to identify a first thermocouple probe of the plurality of thermocouple probes, wherein the first thermocouple probe includes a first positive leg and a first negative leg and is located electrically farthest from the junction box. The method includes calculating a first loop resistance between the first thermocouple probe and the junction box and configuring a second thermocouple probe of the plurality of thermocouple probes having a second positive leg, a second negative leg and a second loop resistance such that the second loop resistance is substantially equal to the first loop resistance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation Application of pending U.S.Non-Provisional patent application Ser. No. 17/175,895 (Docket No.HAR-0001-CIP) filed Feb. 15, 2021 which is a Continuation-In-Partapplication of U.S. Non-Provisional patent application Ser. No.15/441,374 (Docket No. HAR-0001) filed Feb. 24, 2017 and which claimsthe benefit of priority of the filing dates of U.S. Non-Provisionalpatent application Ser. No. 17/175,895 (Attorney Docket No.HAR-0001-CIP), U.S. Non-Provisional Patent Application Serial No.15/441,374 (Attorney Docket No. HAR-0001) and U.S. Provisional PatentApplication Ser. No.: 62/299,060 (Attorney Docket No. HAR-0001-P), filedon Feb. 24, 2016 all of which are incorporated by reference herein intheir entireties.

FIELD OF THE INVENTION

The present invention relates generally to a thermocouple system andmore particularly to a method for optimizing a thermocouple system beingused with gas turbine engines.

BACKGROUND OF THE INVENTION

In the operation of turbo-fan, turbo-shaft, turbo-jet or jet aircraft,the temperature of the aircraft gas or jet stream must be maintained andcontrolled within a critical range; below which insufficient thrust orefficiency is indicated, and above which damage to the engine andaircraft may be caused.

Modern aircraft that are operating at high speeds are known to besubjected to great stress, strain and shock. Accordingly, thethermocouple apparatus must not only be adapted to elevated states andrapid changes of temperature, it must also be characterized by robustdesign and construction to reliably operate at these severeenvironmental conditions. Additionally, the thermocouples have to belocated at points spaced about the periphery of the gas turbine tailcone or pipe in order to obtain meaningful temperature measurements.Furthermore, the thermocouples are mounted about the tail cone or pipeof a gas turbine in such a way that the failure of any one or more ofthe thermocouples does not affect or nullify the functioning of anyother of the thermocouples, and so that their total or averageindication is utilized as the significant value or measurement of gasstream temperature. These multiple thermocouple arrangements areconventionally characterized still further, and in one type by theconnection of resistors in series with the thermocouples to balance orequalize their influence on the indicated output. In another form, theaveraging may be carried out by circuitry or parallel connection of thethermocouples. In either case, the multiple or combined thermocouplearrangement must be capable of continuously operating notwithstandingany damage or single point failures.

Moreover, the design of the thermocouple apparatus, such as hereconcerned, may be governed further by the fact that the temperaturesobtained in any of the several cross-sections of the aircraft gas streammay vary considerably, whereby a meaningful measurement may require theaveraging of a number of readings taken at a number of locations. Thethermocouple signal is transmitted through common terminals to thedesired recording, indicating and controlling instruments, which aretypically remotely located and which are capable of deriving andmeasuring a net electromotive force (E.M.F.). Thus, the thermocouplesand harness apparatuses here concerned typically include a set of heatsensing probes arranged about the tail cone or pipe of a gas turbine,and an assembly of coupled thermocouple wire segments constructed andarranged as electrical connections to the thermocouples. These may serveto transmit the aforementioned signal to the cockpit, EEC and/or otheraircraft equipment.

SUMMARY OF THE INVENTION

Briefly stated, conventional thermocouple harness technology employsequal wire length as a means of balancing the series resistance ofthermocouple channels. This invention utilizes a scientific model toanalyze thermocouple systems and take advantage of the systems' degreesof freedom to optimize designs, which in turn allows significant savingsin wire, weight, size and cost of manufacturing the completethermocouple harnesses.

A Thermocouple System (TCS) is provided and includes a junction box, afirst thermocouple probe, wherein the first thermocouple probe includesa first positive terminal connected with the junction box via a firstpositive leg having a First Positive Harness Wire and a first positiveprobe wire, and a first negative terminal connected with the junctionbox via a first negative leg having a First Negative Harness Wire and afirst negative probe wire. Additionally, a second thermocouple probe isprovided, wherein the second thermocouple probe includes a secondpositive terminal connected with the junction box via a second positiveleg having a Second Positive Harness Wire and a second positive probewire, and a second negative terminal connected with the junction box viaa second negative leg having a Second Negative Harness Wire and a secondnegative probe wire, wherein the TCS includes a total system resistanceand wherein the First Positive Harness Wire includes a first positiveharness wire length, the First Negative Harness Wire includes a firstnegative harness wire length, the Second Positive Harness Wire includesa second positive harness wire length and the Second Negative HarnessWire includes a second negative harness wire length, and wherein atleast one of the first positive harness wire length, second positiveharness wire length, first negative harness wire length and secondnegative harness wire length are configured such that the total systemresistance is balanced between the first thermocouple probe and thesecond thermocouple probe.

A Thermocouple System (TCS) is provided and includes a junction box, afirst thermocouple probe, wherein the first thermocouple probe includesa first positive terminal connected with the junction box via a firstpositive leg and a first negative terminal connected with the junctionbox via a first negative leg, wherein the first positive leg includes afirst positive leg resistance and a First Positive Harness Wire having aFirst Positive Harness Wire length, and the first negative leg includesa first negative leg resistance and a First Negative Harness Wire havinga First Negative Harness Wire length, and at least one additionalthermocouple probe, wherein the at least one additional thermocoupleprobe includes a second thermocouple probe having a second positiveterminal connected with the junction box via a second positive leg and asecond negative terminal connected with the junction box via a secondnegative leg, wherein the second positive leg includes a second positiveleg resistance and a Second Positive Harness Wire having a SecondPositive Harness Wire length and the second negative leg includes asecond negative leg resistance and a Second Negative Harness Wire havinga Second Negative Harness Wire length, and wherein the First NegativeHarness Wire length and Second Negative Harness Wire length areconfigured to be minimized and wherein the sum of the second positiveleg resistance and the second negative leg resistance is substantiallyequal to the sum of the first positive leg resistance and the firstnegative leg resistance.

A method of optimizing a thermocouple system having a plurality ofthermocouple probes and a junction box is provided and includesexamining the thermocouple system to identify a first thermocouple probeof the plurality of thermocouple probes, wherein the first thermocoupleprobe includes a first positive leg and a first negative leg and islocated electrically farthest from the junction box, calculating a firstloop resistance between the first thermocouple probe and the junctionbox and configuring a second thermocouple probe of the plurality ofthermocouple probes having a second positive leg, a second negative legand a second loop resistance such that the second loop resistance issubstantially equal to the first loop resistance.

A wire harness is provided in accordance with an embodiment of theinvention, wherein the wire harness includes a Wire Harness Connector(WHC) having a first WHC positive terminal, a first WHC negativeterminal, a second WHC positive terminal and a second WHC negativeterminal. A first component is included and is electrically connected tothe first WHC positive terminal and the first WHC negative terminal viaa plurality of first component wires, wherein the plurality of firstcomponent wires include a first component wire length and a firstcomponent loop resistance. A second component is included and iselectrically connected to the first WHC positive terminal and the firstWHC negative terminal via a plurality of second component wires, whereinthe plurality of second component wires include a second component wirelength and a second component loop resistance. A third component isincluded and is electrically connected to the first WHC positiveterminal and the first WHC negative terminal via a plurality of thirdcomponent wires, wherein the plurality of third component wires includea third component wire length and a third component loop resistance. Afourth component is included and is electrically connected to the firstWHC positive terminal and the first WHC negative terminal via aplurality of fourth component wires, wherein the plurality of fourthcomponent wires include a fourth component wire length and a fourthcomponent loop resistance.

Additionally, a fifth component is included and is electricallyconnected to the second WHC positive terminal and the second WHCnegative terminal via a plurality of fifth component wires, wherein theplurality of fifth component wires include a fifth component wire lengthand a fifth component loop resistance. A sixth component is included andis electrically connected to the second WHC positive terminal and thesecond WHC negative terminal via a plurality of sixth component wires,wherein the plurality of sixth component wires includes a sixthcomponent wire length and a sixth component loop resistance. A seventhcomponent is included and is electrically connected to the second WHCpositive terminal and the second WHC negative terminal via a pluralityof seventh component wires, wherein the plurality of seventh componentwires include a seventh component wire length and a seventh componentloop resistance and an eighth component is included and is electricallyconnected to the second WHC positive terminal and the second WHCnegative terminal via a plurality of eighth component wires, wherein theplurality of eighth component wires include an eighth component wirelength and an eighth component loop resistance. It should be appreciatedthat at least one of the first component wire length, the secondcomponent wire length, the third component wire length, the fourthcomponent wire length, the fifth component wire length, the sixthcomponent wire length, the seventh component wire length and the eighthcomponent wire length may be configured responsive to at least one ofthe first component loop resistance, the second component loopresistance, the third component loop resistance, the fourth componentloop resistance, the fifth component loop resistance, the sixthcomponent loop resistance, the seventh component loop resistance and theeighth component loop resistance.

A wire harness is provided in accordance with an embodiment of theinvention and includes a Wire Harness Connector (WHC) having a first WHCpositive terminal, a first WHC negative terminal, a second WHC positiveterminal and a second WHC negative terminal. The wire harness furtherincludes a first component electrically connected to the first WHCpositive terminal and the first WHC negative terminal via a plurality offirst component wires, wherein the plurality of first component wiresincludes a first component wire length and a first component loopresistance. The wire harness also includes a fifth componentelectrically connected to the second WHC positive terminal and thesecond WHC negative terminal via a plurality of fifth component wires,wherein the plurality of fifth component wires includes a fifthcomponent wire length and a fifth component loop resistance, wherein atleast one of the first component wire length and the fifth componentwire length are configured responsive to at least one of the firstcomponent loop resistance and the fifth component loop resistance.

A wire harness is provided in accordance with an embodiment of theinvention and includes at least one first component positive wire,wherein the at least one first component positive wire is configured toelectrically connect to a Wire Harness Connector (WHC) positiveterminal, wherein the at least one first component positive wireincludes a first component positive wire length and a first componentpositive wire resistance. The wire harness further includes at least onefirst component negative wire, wherein the at least one first componentnegative wire is configured to electrically connect to a WHC negativeterminal, wherein the at least one first component negative wireincludes a first component negative wire length and a first componentnegative wire resistance. The wire harness also includes at least onesecond component positive wire, wherein the at least one secondcomponent positive wire is configured to electrically connect to the WHCpositive terminal, wherein the at least one second component positivewire includes a second component positive wire length and a secondcomponent positive wire resistance. Additionally, the wire harnessincludes, at least one second component negative wire, wherein the atleast one second component negative wire is configured to electricallyconnect to the WHC negative terminal, wherein the at least one secondcomponent negative wire includes a second component negative wire lengthand a second component negative wire resistance. The wire harness alsoincludes a first component loop resistance and a second component loopresistance, wherein the first component loop resistance includes thefirst component positive wire resistance and the first componentnegative wire resistance, and wherein the second component loopresistance includes the second component positive wire resistance andthe second component negative wire resistance, and wherein at least oneof the first component positive wire length, the first componentnegative wire length, the second component positive wire length and thesecond component negative wire length are configured responsive to atleast one of the first component loop resistance and the secondcomponent loop resistance such that the first component loop resistanceand the second component loop resistance are balanced.

A wire harness is provided wherein the wire harness includes a WireHarness Connector (WHC) having a WHC positive terminal and a WHCnegative terminal, a first component electrically connected to the WHCpositive terminal and the WHC negative terminal via a plurality of firstcomponent wires, wherein the plurality of first component wires includea first component wire length and a first component loop resistance anda second component electrically connected to the first WHC positiveterminal and the first WHC negative terminal via a plurality of secondcomponent wires, wherein the plurality of second component wires includea second component wire length and a second component loop resistanceand wherein at least one of the first component wire length and thesecond component wire length are configured responsive to at least oneof the first component loop resistance and the second component loopresistance.

A method for electrically balancing a wire harness electricallyconnected with a first component and a second component is provided,wherein the wire harness includes a Wire Harness Connector (WHC) havinga WHC positive terminal and a WHC negative terminal, wherein the firstcomponent is electrically connected to the WHC positive terminal and theWHC negative terminal via a plurality of first component wires, whereinthe plurality of first component wires include a first component wirelength and a first component loop resistance and wherein the secondcomponent electrically connected to the first WHC positive terminal andthe first WHC negative terminal via a plurality of second componentwires, wherein the plurality of second component wires include a secondcomponent wire length and a second component loop resistance. The methodincludes determining the first component loop resistance, determiningthe second component loop resistance and configuring at least one of thefirst component wire length and the second component wire length tobalance the resistance of the wire harness.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the present inventionshould be more fully understood from the accompanying detaileddescription of illustrative embodiments taken in conjunction with thefollowing Figures in which like elements are numbered alike in theseveral Figures:

FIG. 1A illustrates a Dual Channel Thermocouple Harness System afteroptimization, in accordance with one embodiment of the invention.

FIG. 1B illustrates a schematic representation of the ChannelThermocouple Harness System of FIG. 1A.

FIG. 1C illustrates a Four Channel Thermocouple Harness System havingfour thermocouple probes after optimization, in accordance with anotherembodiment of the invention.

FIG. 1D illustrates a schematic representation of the Four ChannelThermocouple Harness System of FIG. 1C.

FIG. 1E illustrates a schematic showing the lengths of the positive andnegative lead wires for the Four Channel Thermocouple Harness System ofFIG. 1C.

FIG. 2 illustrates a diagram for a Type-K Thermocouple measurementsystem.

FIG. 3 illustrates an example of an Arbitrary Electrical Conductor.

FIG. 4 is an explanation of one embodiment to compute Resistance of theArbitrary Electrical Conductor.

FIG. 5 illustrates a Cross Section of Arbitrary Electrical Conductor atdistance x.

FIG. 6 illustrates a Thermocouple Output Temperature Gradient PathIndependence via path 1.

FIG. 7 illustrates a Thermocouple Output Temperature Gradient PathIndependence via path 2.

FIG. 8 illustrates a Functional Diagram of Single Probe ThermocoupleSystem.

FIG. 9 illustrates a Thermocouple Thevenin Equivalent Circuit.

FIG. 10 illustrates a Single Channel Thermocouple Equivalent Circuit.

FIG. 11 illustrates a formula for a Single Channel Thermocouple SystemSeries Resistance.

FIG. 12 illustrates a formula for a Single Channel Thermocouple HarnessSeries Resistance 5 Degrees of Freedom.

FIG. 13 is a description for a Dual Channel Thermocouple Harness System,includes Equivalent Electrical Circuit and Layout before OPTIMIZATION(conventional).

FIG. 14 illustrates the Optimized Dual Channel Thermocouple HarnessSystem of FIG. 1A and an Equivalent Electrical Circuit and Layout, inaccordance with one embodiment of the invention.

FIG. 15 illustrates a Functional Diagram of a Thermocouple System with 4Probes connected in parallel.

FIG. 16 illustrates an Equivalent Electrical Schematic of ThermocoupleSystem with 4 Probes connected in parallel.

FIG. 17 illustrates a Layout of Convectional Thermocouple Harness Systemwith 4 Probes connected in parallel.

FIG. 18 illustrates the Optimized Channel Thermocouple Harness System ofFIG. 1B, in accordance with one embodiment of the invention.

FIG. 19 illustrates a “Looped back” wire, in accordance with oneembodiment of the invention.

FIG. 20 illustrates an example of Two Thermocouple Harnesses connectedat Junction Box.

FIG. 21 illustrates an operational block diagram illustrating a methodfor optimizing a Thermocouple Harness System, in accordance with oneembodiment of the invention.

FIG. 22 illustrates a schematic of a wire harness incorporating wireswhere the length of the wires are configured to balance the resistanceof the wire harness, in accordance with one embodiment of the presentinvention.

DETAILED DESCRIPTION

It should be appreciated that the present invention provides a uniquethermocouple system and method of sensing, indicating and controllinggas turbine temperatures and in particular, to the thermocoupleapparatuses such as those employed for measuring, indicating andregulating the temperature of the exhaust or propulsion gas streams ofgas turbines on turbo-fan, turbo-shaft, turbo-jet and/or jet aircraft.The unique methodology of the invention involves optimizing theconfiguration of the harness wires to reduce the length of the wire,thereby reducing weight while preserving the total series resistance ofthe system. Additionally, the unique methodology of the invention may beapplied to systems having any number of Thermocouple Channels. It shouldbe appreciated that the portion of the thermocouple harness thatconnects between the thermocouple probe and the junction box is referredto as a thermocouple “channel” throughout the remainder of thisdocument.

Referring to FIG. 1A, a Dual Channel Thermocouple Harness System 1000that is optimized using the method of the invention described herein isshown in accordance with one embodiment. As shown, the Dual ChannelThermocouple Harness System 1000 includes a first thermocouple probe TC1and a second thermocouple probe TC2, wherein the first thermocoupleprobe TC1 includes a first thermocouple positive terminal 1002 and afirst thermocouple negative terminal 1004 and the second thermocoupleprobe TC2 includes a second thermocouple positive terminal 1006 and asecond thermocouple negative terminal 1008. It should be appreciatedthat the Dual Channel Thermocouple Harness System 1000 further includesa junction box 1010, wherein the first thermocouple positive terminal1002 may be connected with the junction box 1010 via a first positiveleg 1012 having a first positive leg resistance and wherein the secondthermocouple positive terminal 1006 may be connected with the junctionbox 1010 via a second positive leg 1014 having a second positive legresistance. Moreover, the first thermocouple negative terminal 1004 maybe connected with the junction box 1010 via a first negative leg 1016having a first negative leg resistance and the second thermocouplenegative terminal 1008 may be connected with the junction box 1010 via asecond negative leg 1018 having a second negative leg resistance.

Referring to FIG. 1B, a schematic representation of the Dual ChannelThermocouple Harness System 1000 of FIG. 1A is shown. The first positiveleg 1012 includes a TC1 Positive Probe Wire 1020 having an inherentresistance TC1PPR and a First Positive Harness Wire 1022 having aninherent resistance FPHWR, wherein the TC1 Probe is connected to theFirst Positive Harness Wire 1022 via the TC1 Positive Probe Wire 1020.Additionally, the first negative leg 1016 includes a TC1 Negative ProbeWire 1024 having an inherent resistance TC1NPR and a First NegativeHarness Wire 1026 having an inherent resistance FNHWR, wherein the TC1Probe is connected to the First Negative Harness Wire 1026 via the TC1Negative Probe Wire 1024. Accordingly, the first positive leg resistanceincludes the inherent resistance TC1PPR of the TC1 Positive Probe Wire1020 and the inherent resistance FPHWR of the First Positive HarnessWire 1022 and the first negative leg resistance includes the inherentresistance TC1NPR of the TC1 Negative Probe Wire 1024 and the inherentresistance of the First Negative Harness Wire 1026.

Similarly, the second positive leg 1014 includes a TC2 Positive ProbeWire 1028 having an inherent resistance TC2PPR and a Second PositiveHarness Wire 1030 having an inherent resistance SPHWR, wherein the TC2Probe is connected to the Second Positive Harness Wire 1030 via the TC2Positive Probe Wire 1028. Additionally, the second negative leg 1018includes a TC2 Negative Probe Wire 1032 having an inherent resistanceTC2NPR and a Second Negative Harness Wire 1034 having an inherentresistance SNHWR, wherein the TC2 Probe is connected to the SecondNegative Harness Wire 1034 via the TC2 Negative Probe Wire 1032.Accordingly, the second positive leg resistance includes the inherentresistance TC2PPR of the TC2 Positive Probe Wire 1028 and the inherentresistance SPHWR of the Second Positive Harness Wire 1030 and the secondnegative leg resistance includes the inherent resistance TC2NPR of theTC2 Negative Probe Wire 1032 and the inherent resistance SNHWR of theSecond Negative Harness Wire 1034.

It should be appreciated that the First Positive Harness Wire 1022includes a first positive harness wire length FPHWL, the Second PositiveHarness Wire 1030 includes a second positive harness wire length SPHWL,the First Negative Harness Wire 1026 includes a first negative harnesswire length FNHWL and the Second Negative Harness Wire 1034 includes asecond negative harness wire length SNHWL. It should be furtherappreciated that the combined lengths of the FPHWL and the FNHWL and thecombined lengths of the SPHWL and the SNHWL may be configured asdescribed hereinafter to balance the series resistance between TC1 andTC2, while minimizing the lengths of wire being used.

Furthermore, it should be appreciated that the unique methodology of theinvention may be applied to systems having any number of ThermocoupleChannels. For example, referring to FIG. 1C, FIG. 1D and FIG. 1E, aThermocouple Harness System 2000 having four (4) probes connected inparallel is optimized using the method of the invention describedhereinafter is shown in accordance with another embodiment. As shown,the Thermocouple Harness System 2000 includes a first thermocouple probeT2C1, a second thermocouple probe T2C2, a third thermocouple probe T2C3and a fourth thermocouple probe T2C4, wherein the first thermocoupleprobe T2C1 includes a T2C1 thermocouple positive terminal 2002 and aT2C1 thermocouple negative terminal 2004, the second thermocouple probeT2C2 includes a T2C2 thermocouple positive terminal 2006 and a T2C2thermocouple negative terminal 2008, the third thermocouple probe T2C3includes a T2C3 thermocouple positive terminal 2010 and a T2C3thermocouple negative terminal 2012 and the fourth thermocouple probeT2C4 includes a T2C4 thermocouple positive terminal 2014 and a T2C4thermocouple negative terminal 2016.

It should be appreciated that the Thermocouple Harness System 2000further includes a junction box 2018, wherein the T2C1 thermocouplepositive terminal 2002 may be connected with the junction box 2018 via afirst positive leg 2022 having a first positive leg resistance, the T2C2thermocouple positive terminal 2006 may be connected with the junctionbox 2018 via a second positive leg 2024 having a second positive legresistance, the T2C3 thermocouple positive terminal 2010 may beconnected with the junction box 2018 via a third positive leg 2026having a third positive leg resistance and the T2C4 thermocouplepositive terminal 2014 may be connected with the junction box 2018 via afourth positive leg 2028 having a fourth positive leg resistance. Also,the T2C1 thermocouple negative terminal 2004 may be connected with thejunction box 2018 via a first negative leg 2030 having a first negativeleg resistance, the T2C2 thermocouple negative terminal 2008 may beconnected with the junction box 2018 via a second negative leg 2032having a second negative leg resistance, the T2C3 thermocouple negativeterminal 2012 may be connected with the junction box 2018 via a thirdnegative leg 2034 having a third negative leg resistance and the T2C4thermocouple negative terminal 2016 may be connected with the junctionbox 2018 via a fourth negative leg 2036 having a fourth negative legresistance.

Referring to FIG. 1D, a schematic representation of the multi-ChannelThermocouple Harness System 2000 of FIG. 1C is shown. The first positiveleg 2022 includes a T2C1 Positive Probe Wire 2038 having an inherentresistance T2C1PPR and a First Positive Harness Wire 2040 having aninherent resistance FPHWR, wherein the T2C1 Probe is connected to theFirst Positive Harness Wire 2040 via the T2C1 Positive Probe Wire 2038.The first negative leg 2030 includes a T2C1 Negative Probe Wire 2042having an inherent resistance T2C1NPR and a First Negative Harness Wire2044 having an inherent resistance FNHWR, wherein the T2C1 Probe isconnected to the First Negative Harness Wire 2044 via the T2C1 NegativeProbe Wire 2042. Accordingly, the first positive leg resistance includesthe inherent resistance T2C1PPR of the T2C1 Positive Probe Wire 2038 andthe inherent resistance FPHWR of the First Positive Harness Wire 2040and the first negative leg resistance includes the inherent resistanceT2C1NPR of the T2C1 Negative Probe Wire 2042 and the inherent resistanceFNHWR of the First Negative Harness Wire 2044.

The second positive leg 2024 includes a T2C2 Positive Probe Wire 2046having an inherent resistance T2C2PPR and a Second Positive Harness Wire2048 having an inherent resistance SPHWR, wherein the T2C2 Probe isconnected to the Second Positive Harness Wire 2048 via the T2C2 PositiveProbe Wire 2046. The second negative leg 2032 includes a T2C2 NegativeProbe Wire 2050 having an inherent resistance T2C2NPR and a SecondNegative Harness Wire 2052 having an inherent resistance SNHWR, whereinthe T2C2 Probe is connected to the Second Negative Harness Wire 2052 viathe T2C2 Negative Probe Wire 2050. Accordingly, the second positive legresistance includes the inherent resistance T2C2PPR of the T2C2 PositiveProbe Wire 2046 and the inherent resistance SPHWR of the Second PositiveHarness Wire 2048 and the second negative leg resistance includes theinherent resistance T2C2NPR of the T2C2 Negative Probe Wire 2050 and theinherent resistance SNHWR of the Second Negative Harness Wire 2052.

Furthermore, the third positive leg 2026 includes a T2C3 Positive ProbeWire 2054 having an inherent resistance T2C3PPR and a Third PositiveHarness Wire 2056 having an inherent resistance TPHWR, wherein the T2C3Probe is connected to the Third Positive Harness Wire 2056 via the T2C3Positive Probe Wire 2054. The third negative leg 2034 includes a T2C3Negative Probe Wire 2058 having an inherent resistance T2C3NPR and aThird Negative Harness Wire 2060 having an inherent resistance TNHWR,wherein the T2C3 Probe is connected to the Third Negative Harness Wire2060 via the T2C3 Negative Probe Wire 2058. Accordingly, the thirdpositive leg resistance includes the inherent resistance T2C3PPR of theT2C3 Positive Probe Wire 2054 and the inherent resistance TPHWR of theThird Positive Harness Wire 2056 and the second negative leg resistanceincludes the inherent resistance T2C3NPR of the T2C3 Negative Probe Wire2058 and the inherent resistance TNHWR of the Third Negative HarnessWire 2060.

The fourth positive leg 2028 includes a T2C4 Positive Probe Wire 2062having an inherent resistance T2C4PPR and a Fourth Positive Harness Wire2064 having an inherent resistance QPHWR, wherein the T2C4 Probe isconnected to the Fourth Positive Harness Wire 2064 via the T2C4 PositiveProbe Wire 2062. The fourth negative leg 2036 includes a T2C4 NegativeProbe Wire 2066 having an inherent resistance T2C4NPR and a FourthNegative Harness Wire 2068 having an inherent resistance QNHWR, whereinthe T2C4 Probe is connected to the Fourth Negative Harness Wire 2068 viathe T2C4 Negative Probe Wire 2066. Accordingly, the fourth positive legresistance includes the inherent resistance T2C4PPR of the T2C4 PositiveProbe Wire 2062 and the inherent resistance QPHWR of the Fourth PositiveHarness Wire 2048 and the fourth negative leg resistance includes theinherent resistance T2C4NPR of the T2C4 Negative Probe Wire 2066 and theinherent resistance QNHWR of the Fourth Negative Harness Wire 2068.

It should be appreciated that the First Positive Harness Wire 2040includes a first positive harness wire length FPHWL, the Second PositiveHarness Wire 2048 includes a second positive harness wire length SPHWL,the Third Positive Harness Wire 2056 includes a third positive harnesswire length TPHWL and the Fourth Positive Harness Wire 2064 includes afourth positive harness wire length QPHWL. Moreover, the First NegativeHarness Wire 2044 includes a first negative harness wire length FNHWL ,the Second Negative Harness Wire 2052 includes a second negative harnesswire length SNHWL, the Third Negative Harness Wire 2060 includes a thirdnegative harness wire length TNHWL and the Fourth Negative Harness Wire2068 includes a fourth negative harness wire length QNHWL. It should beappreciated that the series resistance of the FPHWL and the FNHWL, theseries resistance of the SPHWL and the SNHWL, the series resistance ofthe TPHWL and the TNHWL and the series resistance of the QPHWL and theQNHWL may be configured as described hereinafter to balance the parallelresistance between T2C1, T2C2, T2C3 and T2C4, while minimizing thelengths of wire being used.

It should be appreciated that the method of optimizing the thermocoupleharness system 1000, 2000 may be accomplished as described hereinafterwith reference to the several figures. Referring to FIG. 2, oneembodiment of a Type-K thermocouple measurement article is provided andmay apply to all thermocouple types (J, K, T, E, N, R, S, B, G, C andD). Referring to FIG. 8, a functional diagram of a single probethermocouple system is shown and FIG. 9 illustrates an equivalentelectrical circuit for a thermocouple system. Referring to FIG. 9, anequivalent electrical circuit for a thermocouple system (or channel) 100is shown and includes a positive probe lead 101 and a negative probelead 102, and for analysis can be represented as a DC voltage source 104and a Thevenin series resistance 103. The equivalent series resistance103 may include all resistances in the circuit, including, but notlimited to, the following: weld joints, solder joints, probe leads,wires, terminals, contacts, contact-to-contact resistances, discreteresistors and all parasitic resistances in the system. Referring to FIG.10, one embodiment of a simplified single channel Thermocouple Systemequivalent circuit 200 is shown, which is used here as an electricalmodel to analyze thermocouple systems. The model includes probe leadresistances (R_(PCr) 201 & R_(Pal) 202), harness wire resistances(R_(HCr) 203 & R_(Hal) 204) and a load resistance 205. Typically, theload resistance 205 may be greater than 100 kΩ, hence the thermocoupletotal series resistance is typically designed to be below 20 Ω, sincethe Special Limits accuracy is 0.4% for Type-K thermocouples. FIG. 15shows the functional diagram of Thermocouple System 300 with 4 Probes301,302,303 and 304 connected in parallel. FIG. 16 illustrates theequivalent electrical circuit schematic of Thermocouple System with 4probes connected in parallel. The Thermocouple Probes are connected inparallel with thermocouple wires (hereinafter referred to as a harness).Wires from each probe are connected at a thermocouple junction 307,which automatically performs a signal averaging function. As explainedabove, in order to produce a true average signal, series resistances ofall channels must be balanced (equal to each other within a typicaltolerance of approximately 5%). If one of the channels has a lowerresistance, it will have a greater influence on output the signal (notrepresentative of a true average signal).

Conventional Thermocouple Harness Configuration

A thermocouple harness is defined herein as a collection of wiresintegrated into a flexible assembly, providing connection betweenindividual probes and the rest of the thermocouple system components. Anexample of an actual thermocouple harness assembly 400 is shown in FIG.20, which includes left thermocouple harness 401, right thermocoupleharness 402 and junction box 403. FIG. 17 shows the conventionalconfiguration of an Exhaust Gas Temperature system 500. The systemincludes 4 probes 501, 502, 503 and 504 circumferentially located on 60″diameter section of a gas turbine, in many instances the probes have twofully isolated, independent channels for system redundancy. AveragingJunctions 506 are inside Thermocouple Junction Box assembly 505, andconnections are carried out by means of terminal lugs and studs.Terminal lugs are of the same thermocouple materials as the thermocouplewires. Studs, nuts and washers do not need to be made from thermocouplematerial. The length of wires connecting TC1 501 (in FIG. 17) and theJunction Box 505 is 80″. The distance between TC2 502 and the JunctionBox 505 is 30″. To balance resistance between probes TC1 501 and TC2502, fifty inches of “looped back” wire 601 and 602 are used as shown inFIG. 19. Note that bundle thickness of thermocouple harness in FIG. 19is 6 wires thick, due to loopback wires. The total thermocouple wireused in the configuration shown in FIG. 19 is 640″. Furthermore, totalamount of wire used for resistance balance is 200″. Note that in FIG. 2Chromel (NiCr) has approximately 2.4 times (although referred tohereinafter as 2.4) the resistivity of Alumel (NiAl), meaning that 1.0inch of Chromel wire has same resistance as 2.4 inches of Alumel wire(of the same gage), that is one of the tools which will be used in thisinvention as part of design optimization in reduction of weight and sizeinefficiencies of thermocouple harness shown in FIG. 19.

Length optimization method for Type-K thermocouple harness: NiCr has 2.4greater Ohms/inch than NiAl for same gage wire. In thermocouple systemwith fixed series resistance, increasing NiCr length by 1 inch allows todecrease NiAl length by 2.4 inches, yielding 1.4 inch/inch reduction.For example if NiCr is increased by 21 inches, Ni Al can be reduced by50 inches while total series resistance is preserved and 29 inches ofwire is saved.

Cross-sectional area optimization method for Type-K thermocoupleharness: In thermocouple system with fixed series resistance, decreasingcross-sectional area on of harness lead will allow reduction inOhms/inch of harness wire. For example in thermocouple harness with NiCrand NiAl 80 inches long and with AWG18(19/30) wire, series resistance is2.16 (fixed in this example). Changing the NiCr and NiAl wires toAWG20(19/32) will require 51.4 inches to preserve series resistance of2.16 ohms. This method yielded wire length reduction of 28.6 inches onNiCr and also on NiAl, which is 35.75%. Weight will be reduced byadditional 16% because AWG20(19/32) wire is 84% weight per inch ofAWG18(19/30).

It should be appreciated that this invention heavily relies on thetheoretical physics related to electrical resistance and the potentialfield in the thermocouple wire which is caused by the Seebeck effect. Ingeneral, calculating resistance of conductors is very complicated. Theresistance of a given object depends primarily on two factors; whatmaterial it is made of, and its shape. For a given material, theresistance is inversely proportional to the cross-sectional area; forexample, a thick copper wire has lower resistance than anotherwise-identical thin copper wire. Also, for a given material, theresistance is proportional to the length; for example, a long copperwire has higher resistance than an otherwise-identical short copperwire. In general conductors have arbitrary shapes, hence cross-sectionalarea is variable. FIG. 3 below shows an arbitrary geometry conductor700, where electrical current 701 flows in the x direction.

Total resistance of the conductor is the sum of finite sections withvery small thickness, dx, at distance x from origin (x=0) as shown FIG.4. A(x) is the cross section of the conductor at a distance x from theorigin perpendicular to current flux vector as shown in FIG. 5. Toapproximately compute the resistance, the conductor is divided into nsections. In each i-th section, an average resistivity is ρ_(i) andaverage area is A_(i) R_(i) is calculated using ρ_(i) and A_(i), thenall Ri are summed: below:

$\begin{matrix}{{R \approx {\sum\limits_{i = 0}^{n}\left\lbrack R_{i} \right\rbrack}} = {\sum\limits_{i = 0}^{n}\left\lbrack {\rho_{i} \times \frac{\Delta x}{A_{i}}} \right\rbrack}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

Increasing number of sections, n, and decreasing Δx, will increase theaccuracy of computed resistance. Taking limit with Δx becominginfinitely small, the sum becomes an integral:

$\begin{matrix}{{\sum\limits_{\underset{{l\;{im}\mspace{11mu}\Delta\; x}\rightarrow 0}{i = 0}}^{n}\left\lbrack {\rho_{i} \times \frac{\Delta\; x}{A_{i}}} \right\rbrack} = {\int\limits_{x = 0}^{x = l}{{\rho(x)} \times \frac{dx}{A(x)}}}} & {{Equation}\mspace{14mu} 2}\end{matrix}$

That will yield the final formula for computing resistance:

$\begin{matrix}{R = {\int\limits_{x = 0}^{x = l}{{\rho(x)} \times \frac{dx}{A(x)}}}} & {{Equation}\mspace{14mu} 3}\end{matrix}$

Resistance computations may become very complicated, and in some casesrequire computer aid. Fortunately in the case of thermocouple harnesses,valid approximations and simplifications can be done. Resistivity onthermocouple materials is well-controlled by manufacturers. Most harnessmanufacturing companies validate resistivity as a part of their qualityprocess, hence ρ(x) can be assumed to be constant as ρ. Thermocouplewire used in the manufacturing of thermocouple harnesses is purchasedagainst American Wire Gage standards, which are accurately controlled bymanufacturers. Cross section of the wire used for manufacturingthermocouple harnesses can be assumed constant for a given section ofwire with a specified gage, hence A(x) can be assumed constant as A, asshown in equation below:

$\begin{matrix}{{\int\limits_{x = 0}^{x = l}{{\rho(x)} \times \frac{dx}{A(x)}}} = {\frac{\rho}{A} \times {\int\limits_{x = 0}^{x = l}{dx}}}} & {{Equation}\mspace{14mu} 4}\end{matrix}$

The resistance, R, and conductance, G, of a conductor of uniform crosssection, therefore, can be computed as:

$\begin{matrix}{R = {\rho \times \frac{l}{A}}} & {{Equation}\mspace{14mu} 5}\end{matrix}$

Where l is the length of the conductor, A is the cross-sectional area ofthe conductor, and ρ is the electrical resistivity (also called specificelectrical resistance). A key attribute of a reliable and accuratethermocouple harness system is that it operates under a conservativevector field. Consider a vector field ν,

ν=∇φ  Equation 6

Where represents a scalar field and ∇φ represents the gradient of thefield. A conservative vector field requires that the line integralbetween two points, A and B, is path independent, as:

∫_(A) ^(B) ν·dr=φ(B)−φ(A)   Equation 7

This invention exploits the phenomena of path independence inthermocouple harnesses, which allows us to use the design degrees offreedom to optimize the design. In thermocouple system applicationvector field φ is electrical field E (volts/meter) and scalar potentialν is electrical potential V(volts). The implication of conservativefield theory on thermocouple systems, is that the output signal isdependent on ΔT only (where ΔT is T1-T2), as shown in FIG. 6 and FIG. 7.FIG. 6 and FIG. 7 show that metal 2 lead can be routed via Path 1 orPath 2, thermocouple signal will be identical. Path 1 and Path 2 canhave different wire gage, length, temperature gradient, seriesresistance, and still thermocouple output will be identical.

Following section provides detailed analytical examples for thisinvention.

This analysis provides design optimization example for single, dual andquad thermocouple systems. Same approach applies to any size system.

Single Channel Thermocouple System

FIG. 10 shows a Single Channel Thermocouple System Equivalent Circuit.The total series resistance of the channel is the sum of RPCr 201, RPA1202, RHCr 203 and RHA1 204. The complete formula for the total seriesresistance computation is shown in FIG. 11, noting that joints andparasitic resistances are excluded. In this invention, we are concernedwith harness optimization; hence the three last terms 890 will be usedin the analysis. FIG. 12 shows the analytical model for single channelthermocouple harness with total series resistance Rs 800. Sincethermocouple material must be used, the model has five (5) degrees offreedom, which are the following: Length of the positive lead 801,length of the negative lead 802, cross-sectional area of the positivelead 803, cross-sectional area of the negative lead 804 and discreteresistor 805. Note that p-positive 806 and p-negative 807 are fixed forthermocouple designs, thus are not considered degrees of freedom. Thisinvention makes use of these above five degrees of freedom 801, 802,803, 804 and 805 to optimize thermocouple harness designs.

Convention Harness Design

The Thermocouple Harness 200 in FIG. 10 is constructed from AWG18(19/30)80.0″ long K-Type leads. Positive (NiCr) lead 203 has resistance ofapproximately 0.019 Ω/inch. Negative (NiAl) lead 204 has resistance ofapproximately 0.008 Ω/inch. Total series resistance is 2.16 Ω.

Taking advantage of Length as degree of freedom: The optimization isdone on Thermocouple Harness 200 in FIG. 10. The approach based on thesection “Length optimization method Type-K thermocouple harness”, whichallows optimization of the total wire length by modifying length of NiCr203 and NiAl 204 leads (degrees of freedom) while series resistance ispreserved. After optimization Thermocouple Harness 200 from FIG. 10becomes 101.05″ AWG18(19/30) NiCr wire (formerly 203) and 30.0″AWG18(19/30) NiAl wire (formerly 204) still yields same 2.16 Ω totalseries resistance. The total wire used in optimized configuration is131.1″, which is 28.95″ length reduction and 18% weight savings, whileseries resistance was preserved.

Taking advantage of Cross-Sectional Area as degree of freedom: Theoptimization is done on Thermocouple Harness 200 in FIG. 10. Theapproach is based on the section “Cross-sectional area optimizationmethod for Type-K thermocouple harness”, which allows optimization ofthe total wire length by modifying cross-sectional of NiCr 203 and NiAl204 leads (degrees of freedom) while series resistance is preserved.After optimization Thermocouple Harness with 51.4″ AWG20(19/32) NiCrwire (formerly 203) and 51.4″ AWG20(19/32) NiAl wire (formerly 204)yields same 2.16 Ω total series resistance. The total wire used in thisconfiguration is 102.8″, which is 57.2″ reduction and 46% weightsavings, while series resistance was preserved.

Using Discrete Resistors as degree of freedom: An alternate approach toincrease series resistance is to add a discrete resistor 805 in serieswith thermocouple wire. For example, to achieve a desired seriesresistance of 3 Ω, add a 0.84 Ω resistor to conventional configuration.This method has advantage of having negligible increase in weight.Discrete resistor 805 may be part of the wiring assembly or implementedinside the thermocouple probe as discterete resistor or part of probeinternal wiring (870 or 880, or combination of 870 and 880).

Summary For Single Channel System

Using length, cross-section and discrete components provides powerfultools in the design and optimization of thermocouple harnesses. Thisinvention uses any of the methods of length, cross-section and discreteresistor manipulation, or any of the combinations with length,cross-section and discrete resistors. To maintain system accuracy due toload resistance, total series resistance should be below 20 Ω, aspreviously noted.

Two Channel Parallel Thermocouple System

The two-channel parallel system requires preserving all designguidelines that apply to the single channel system. In addition, channelresistances must be balanced (within 5% of each other), otherwise one ofthe channels will have greater influence, therefore not a true average.FIG. 13 shows a Dual Channel Thermocouple System Equivalent Circuit andLayout. TC1 901 is 80.0″ away from junction box 909. TC2 902 is 30.0″away from junction box 909. Equivalent Series loop resistance betweenTC1 901 and Junction Box 909 is the sum of TC1 positive lead 910 and TC1negative lead 911 is 2.16 Ω. Since channels must be balanced EquivalentSeries loop resistance between TC2 902 and Junction Box 909 is the sumof TC2 positive lead 912 and TC2 negative lead 913 must be 2.16 Ω. Notethat joints and parasitic resistances are excluded.

FIG. 12 show the analytical model which applies to each of the twothermocouple channels. Since thermocouple material must be used, themodel has five (5) degrees of freedom for each channel as shown in FIG.13. For channel 1 these degrees of freedom are: Length of the positivelead 903, length of the negative lead 904, cross-sectional area of thepositive lead 903, cross-sectional area of the negative lead 904 and adddiscrete resistor. For channel 2 these degrees of freedom are: Length ofthe positive lead 905, length of the negative lead 906, cross-sectionalarea of the positive lead 905, cross-sectional area of the negative lead906 and add discrete resistor. Thermocouple probes 901 and 902 areassumed to have same series resistance, hence can be omitted inanalysis.

Conventional Two Channel Parallel System

As shown in the layout of FIG. 13, the positive lead 903 and negativelead 904 of TC1 901 are equal and are constrained by engine geometry,80″ long. In order to balance series resistance between TC2 902 andJunction Box 909 to resistance between TC1 901 and Junction Box 909,additional two 50.0″ wires are required. Balance resistance wires areTC2 positive 908 and TC2 negative 907 “looped back” leads. In total,100″ of expensive nickel alloy resistance balance wire is used inconventional configuration thermocouple system, as shown in FIG. 13.

Taking advantage of Length as a degree of freedom: The optimization isdone on Thermocouple Harness 900 in FIG. 13. The approach based on thesection “Length optimization method Type-K thermocouple harness”, whichallows optimization of the total wire length by modifying length of NiCr905 and NiAl 906 leads (degrees of freedom) while series resistancebetween TC2 probe 902 and Junction Box 909 is preserved. Afteroptimization Thermocouple Harness 900 from FIG. 13 becomes 101.05″AWG18(19/30) NiCr wire (formerly 905) and 30.0″ AWG18(19/30) NiAl wire(formerly 906) still yields same 2.16 Ω total series resistance. Thetotal wire used in this configuration is 291.1″, which is a 28.9″ lengthreduction and 10% weight savings. FIG. 14 shows optimized system. NiAllooped back wire 907 was eliminated (saving 50 inches of wire), whileNiCr looped back wire 908 increased by 21.05 inches only. Maximum bundlesize 914 decreased from 6 wires thick to 4 wires thick 950.

Taking Advantage of Cross-Sectional Area as Degree of Freedom

The optimization is done on Thermocouple Harness 900 shown in FIG. 13.On TC1 channel with 80.0″ AWG18(19/30) NiCr wire 903 and 80.0″AWG18(19/30) NiAl wire 904 series resistance is 2.16 Ω, these lengthsare driven by engine geometry and cannot be reduced. The optimizationapproach is based on the section “Cross-sectional area optimizationmethod for Type-K thermocouple harness”, which allows optimization ofthe total wire length by modifying cross-sectional of NiCr 905 and NiAl906 leads (degrees of freedom) while series resistance is preserved (tokeep TC1 and TC2 channels balanced). After optimization ThermocoupleHarness with 51.4″ AWG20(19/32) NiCr wire (formerly 905) and 51.4″AWG20(19/32) NiAl wire (formerly 906) yields same 2.16 Ω total seriesresistance. Note that TC1 wires 903 and 904 remain unchanged asAWG18(19/30) with length of 80 inches. The total wire used in thisconfiguration is 262.8″, which is 57.2″ reduction and 23% weightsavings.

Taking advantage of Cross-Section Area and Length as degree of freedom

This section explains how to take advantage of Cross-Section Area andLength optimization simultaneously. The optimization is done onThermocouple Harness 900 shown in FIG. 13. On TC1 channel with 80.0″AWG18(19/30) NiCr wire 903 and 80.0″ AWG18(19/30) NiAl wire 904 seriesresistance is 2.16 Ω, these lengths are driven by engine geometry andcannot be reduced. Step 1: The optimization approach is based on thesection “Cross-sectional area optimization method for Type-Kthermocouple harness” optimizing TC2 both wires 905 and 906 from 80inches long to 51.4 inches long both. Step 2: The approach based on thesection “Length optimization method Type-K thermocouple harness”. Thisis done by reducing NiAl wire (formerly 906) to 30 inches long andincreasing NiCr with (formerly 905) to 60.4 inches long. Afteroptimization Thermocouple Harness 900 from FIG. 13 becomes 60.4″AWG20(19/32) NiCr wire (formerly 905) and 30.0″ AWG20(19/32) NiAl wire(formerly 906) still yields same 2.16 Ω total series resistance. Thetotal wire used in this configuration is 250.4″, which is 69.6″reduction and 26% weight savings.

FIG. 14 shows an optimized system. NiAl looped back wire 907 waseliminated (saving 50 inches of wire), while NiCr looped back wire 908is decreased by 19.6 inches. Maximum bundle size 914 decreased from 6AWG18(19/30) wires thick with to 4 wires AWG20(19/32) thick 950.

Using Discrete Resistors as Degree of Freedom:

This optimization is done on thermocouple harness 900 shown in FIG. 13,by adding series discrete resistor (one or more) between TC2 902 andJunction Box 909. On TC1 channel with 80.0″ AWG18(19/30) NiCr wire 903and 80.0″ AWG18(19/30) NiAl wire 904 series resistance is 2.16 Ω, theselengths are driven by engine geometry and cannot be reduced. Theoptimization to conventional configuration of FIG. 13 is carried out byadding a series 1.35 Ω resistance (by one or more discrete resistors) toTC2 positive lead 905 or negative lead lead 906. Total wire used in thisconfiguration is 220″, which is 100″ length reduction and 31% weightsavings.

Four Channel Parallel Thermocouple System

The four-channel parallel thermocouple system requires preserving alldesign guidelines that apply to the single and dual channel systems.Channel resistances must be balanced (within 5% of each other),otherwise one of the channels will have greater influence (not trueaverage) and equivalent series resistance should be less or equal to 20Ω. FIG. 16 shows a Quad Channel Thermocouple System Equivalent Circuit960. TC1 961 & TC4 968 is 80.0″ away from junction box 962. TC2 963 &TC3 971 is 30.0″ away from junction box 962. Equivalent Series loopresistance between TC1 961 & TC4 968 and Junction Box 962 is the sum ofTC1 positive lead 964 & TC1 negative lead 965 and TC4 positive lead 969and TC4 negative lead 970 is 2.16 Ω. These lengths are driven by enginegeometry and cannot be reduced.

Since all channels must be balanced Equivalent Series loop resistancebetween TC2 963 and Junction Box 962 is the sum of TC2 positive lead 966and TC2 negative lead 967 and must be 2.16 Ω Equivalent Series loopresistance between TC3 971 and Junction Box 962 is the sum of TC3positive lead 972 and TC3 negative lead 973 and must be 2.16 Ω. Notethat joints and parasitic resistances are excluded. FIG. 12 show theanalytical model which applies to each of the four thermocouplechannels. Since thermocouple material must be used, the model has five(5) degrees of freedom for each channel shown in FIG. 16. Since TC1 961and TC4 968 are constrained by engine geometry, these degrees of freedomoptimization apply to TC2 963 & TC3 971: Length of the positive leads966 & 972, length of the negative leads 967 & 973, cross-sectional areaof the positive leads 966 & 972, cross-sectional area of the negativeleads 967 & 973 and discrete series resistors. Thermocouple probes 961,963, 968 and 971 are assumed to have same series resistance, hence canbe omitted in analysis.

Conventional Four Channel Thermocouple Parallel System

As shown in the layout of FIG. 17 the TC1 positive lead 507 and negativelead 508 of TC1 501 are equal and are constrained by engine geometry,which is 80″ long and series resistance of 2.16 Ω. Also as shown in thelayout of FIG. 17 the TC4 positive lead 509 and negative lead 510 of TC4504 are equal and are constrained by engine geometry, which is 80″ longand series resistance of 2.16 Ω. In order to balance series resistancebetween TC2 502 and Junction Box 505, series resistance between TC3 503and Junction Box 505 to resistance between TC1 501 and Junction Box 505and resistance between TC4 504 and Junction Box 505, additional four50.0″ wires are required (shown as “looped back” wires 511, 512, 513 &514. Balance resistance on 511, 512, 513 & 514 add in total 200″ ofexpensive nickel alloy wire in conventional configuration thermocouplesystem, as shown in FIG. 17.

Taking advantage of Length as degree of freedom: The optimization isdone on Thermocouple Harness 500 in FIG. 17. The approach based on thesection “Length optimization method Type-K thermocouple harness”, whichallows optimization of the total wire length by modifying length of NiCr511 and NiAl 512 leads (degrees of freedom) while series resistancebetween TC2 probe 502 and Junction Box 505 is preserved. Also, bymodifying length of NiCr 513 and NiAl 514 leads (degrees of freedom)while series resistance between TC3 probe 502 and Junction Box 505 ispreserved. After optimization Thermocouple Harness 500 from FIG. 17becomes 101.05″ AWG18(19/30) NiCr wires (512 and 514) and 30.0″AWG18(19/30) NiAl wires (formerly 511 and 513) still yields same 2.16 Ωtotal series resistance.

Optimized design is shown in FIG. 18. Note that TC2 NiCr wire 512 andTC3 NiCr wire 514 are longer (changed from 80″ to 101.05″). Also notethat TC2 NiAl wire 515 and NiA wire 516 are 30″ long, representinglength optimization result. The total wire used in this configuration is582.2″, which is 57.9″ length reduction and 9% weight savings. Maximumbundle size 525 before optimization (FIG. 17) is decreased from 6 wiresthick to 4 wires thick 550 after optimization (FIG. 18).

Taking advantage of Cross-Section Area as degree of freedom: Theoptimization is done on Thermocouple Harness 500 shown in FIG. 17. OnTC1 501 channel with 80.0″ AWG18(19/30) NiCr wire 507 and 80.0″AWG18(19/30) NiAl wire 508 series resistance is 2.16 Ω, these lengthsare driven by engine geometry and cannot be changed without affectingseries resistance. Also On TC4 504 channel with 80.0″ AWG18(19/30) NiCrwire 509 and 80.0″ AWG18(19/30) NiAl wire 510 series resistance is 2.16Ω, these lengths are driven by engine geometry and cannot be changedwithout affecting series resistance. The optimization approach is basedon the section “Cross-sectional area optimization method for Type-Kthermocouple harness”, which allows optimization of the total wirelength by modifying cross-sectional of NiCr 512 & 514 and NiAl 511 & 513leads (degrees of freedom) while series resistance is preserved (to keepTC1 and TC2 channels balanced). After optimization Thermocouple Harnesswith 51.4″ AWG20(19/32) NiCr wires (formerly 512 & 514) and 51.4″AWG20(19/32) NiAl wire (formerly 511 & 513) yields same 2.16 Ω totalseries resistance. Note that TC1 wires 507 & 508 and TC4 wires 509 & 510remain unchanged as AWG18(19/30) with length of 80 inches. The totalwire used in this configuration is 525.6″, which is 114.4″ reduction and39% weight savings.

Taking advantage of Cross-Section Area and Length as degree of freedom:This section explains how to take advantage of Cross-Sectional Area andLength optimization simultaneously. The optimization is done onThermocouple Harness 500 shown in FIG. 17. On TC1 501 channel with 80.0″AWG18(19/30) NiCr wire 507 and 80.0″ AWG18(19/30) NiAl wire 508 seriesresistance is 2.16 Ω, these lengths are driven by engine geometry andcannot be changed without affecting series resistance. Also On TC4 504channel with 80.0″ AWG18(19/30) NiCr wire 509 and 80.0″ AWG18(19/30)NiAl wire 510 series resistance is 2.16 Ω, these lengths are driven byengine geometry and cannot be changed without affecting seriesresistance. Step 1: The optimization approach is based on the section“Cross-sectional area optimization method for Type-K thermocoupleharness” optimizing TC2 502 both wires 511 and 512 from 80 inches longto 51.4 inches long both. Also optimizing TC3 503 both wires 513 and 514from 80 inches long to 51.4 inches long both, while equivalent seriesresistance value is preserved. Step 2: The approach based on the section“Length optimization method Type-K thermocouple harness”. This is doneby reducing NiAl wires (formerly 511 and 513) to 30 inches long andincreasing NiCr wires (formerly 512 and 514) to 60.4 inches long, whileequivalent series resistance value is preserved. After optimizationThermocouple Harness 500 from FIG. 16 becomes 60.4″ AWG20(19/32) NiCrwires (formerly 512 and 514) and 30.0″ AWG20(19/32) NiAl wires (formerly511 and 513) still yields same 2.16 Ω total series resistance. TC1 wires507 and 508 and TC4 wires 509 and 510 all stay unchanged as AWG18(19/30)gage and 80 inches long with same 2.16 Ω total series resistance. Thetotal wire used in this configuration is 500.8″, which is 138.4″reduction and 42% weight savings.

Using Discrete Resistors as degree of freedom: Adding in series two 1.35Ω discrete resistors to TC2 and TC3 positive lead (or negative) toconventional configuration Total wire used in this configuration is440″, which is 200″ length reduction and 31% weight savings.

Referring to FIG. 21, an operational block diagram illustrating a method3000 for optimizing a thermocouple system, in accordance with oneembodiment of the invention is shown. It should be appreciated that insome situations the location of the junction box and the thermocoupleprobes may be dependent on the configuration of the architecture of theenvironment within which the thermocouple system is located. The method3000 includes identifying which Thermocouple (TC) probe is located thefarthest from the Junction Box (JB), as shown in operational block 3002.The wire lead loop between this TC probe and the Junction Box isreferred to Channel 1. If possible, each of the positive and negativelead wires for channel 1 may be straight and free of loops. The totalloop resistance of channel 1 is then determined, as shown in operationalblock 3004. This may be accomplished as described herein above usingequation (5) (R=ρ×l/A). Additionally, it is contemplated that any othermethod for determining loop resistance may be used if desired. A secondTC probe is identified and configured such that the negative lead wirebetween the TC probe and the Junction Box may be straight and withoutloops, as shown in operational block 3006. The positive lead wire ofchannel 2 is then configured such that the total loop resistance ofchannel 2 is equal to the total loop resistance of channel 1, as shownin operational block 3008. This is repeated for each additional TC probein the system such that the total system resistance is balanced.

Referring to FIG. 22, one embodiment of a schematic for a wire harness5000 is shown having a plurality of components T/C1, T/C2, T/C3 andT/C4. In this case, schematic 5000 is configured to operate with two (2)channels, wherein each channel is configured to operate with four (4)thermocouples (for a total of eight (8) thermocouples). For example, thefirst component T/C1 includes a first thermocouple 5002 (A-AL, A-CR) anda second thermocouple 5004 (B-AL, B-CR) and a second thermocouple 5002(A-AL, A-CR), the second component T/C2 includes a third thermocouple5006 (A-AL, A-CR) and a fourth thermocouple 5008 (B-AL, B-CR), the thirdcomponent T/C3 includes a fifth thermocouple 5010 (A-AL, A-CR) and asixth thermocouple 5012 (B-AL, B-CR) and the fourth component T/C4includes a seventh thermocouple 5014 (A-AL, A-CR) and an eighththermocouple 5016 (B-AL, B-CR), wherein the thermocouples designatedwith A-AL and A-CR operate on one channel and the thermocouplesdesignated with B-AL and B-CR operate on the other channel. As can beseen, the wire harness 5000 also includes a harness connector 5018having a first channel positive connector 5020, a first channel negativeconnector 5022, a second channel positive connector 5024 and a secondchannel negative connector 5026, wherein the harness connector 5018 isconfigured to electrically interface with the system that the wireharness 5000 is associated.

It should be appreciated that each of the positive legs A-CR of thefirst thermocouple 5002, third thermocouple 5006, fifth thermocouple5010 and seventh thermocouple 5014 are electrically connected to thefirst channel positive connector 5020 via one or more first channelcomponent positive wires and each of the negative legs A-AL of the firstthermocouple 5002, third thermocouple 5006, fifth thermocouple 5010 andseventh thermocouple 5014 are electrically connected to the firstchannel negative connector 5022 via one or more first channel componentnegative wires. It should be further appreciated that each of thepositive legs A-CR of the second thermocouple 5004, fourth thermocouple5006, sixth thermocouple 5012 and eighth thermocouple 5016 areelectrically connected to the second channel positive connector 5024 viaone or more second channel component positive wires and each of thenegative legs A-AL of the second thermocouple 5004, fourth thermocouple5006, sixth thermocouple 5012 and eighth thermocouple 5016 areelectrically connected to the second channel negative connector 5026 viaone or more second channel component negative wires.

It should be appreciated that each of the first channel positive wires,first channel negative wires, second channel positive wires and secondchannel negative wires include a wire length and a wire resistance.Thus, in accordance with an embodiment of the present invention one ormore of the wire lengths of the first channel positive wires, firstchannel negative wires, second channel positive wires and/or secondchannel negative wires may be configured to balance the channel and/orsystem as desired and as described hereinabove. It should be appreciatedthat if the method of the invention is applied to wire harnesses havingonly one channel, then in accordance with an embodiment of the presentinvention, one or more of the wire lengths of the positive wires and/ornegative wires connecting the components (i.e. thermocouples) to theharness connector 5018 may be configured to balance the system asdesired and as described hereinabove.

It should be appreciated that while the present invention has beendescribed as being applicable to a wire harness for thermocouples, themethod and article of the present invention may also be applicable towire harnesses configured to operate with various other types ofcomponents, as desired. Additionally, it is contemplated that thepresent invention may apply to wire harnesses having one or morechannels and two (2) or more components and/or thermocouples, asdesired, and is not limited to configurations having two (2) channelsand four (4) components (eight (8) thermocouples).

It should be appreciated that the architecture of the engine or areawithin which the probes are located may dictate whether the lead wires(positive and/or negative) are straight or have loops. Accordingly, thelength of the lead wires (positive and/or negative) may be adjusted asdescribed herein above to minimize the lead wire length while balancingthe total system resistance.

While the invention has been described with reference to an exemplaryembodiment, it should be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention.Moreover, the embodiments or parts of the embodiments may be combined inwhole or in part without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from thescope thereof. Therefore, it is intended that the invention not belimited to the particular embodiment disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the appendedclaims. Moreover, unless specifically stated any use of the terms first,second, etc. do not denote any order or importance, but rather the termsfirst, second, etc. are used to distinguish one element from another.

What is claimed is:
 1. A wire harness, comprising: a Wire HarnessConnector (WHC) having a WHC positive terminal and a WHC negativeterminal; a first component electrically connected to the WHC positiveterminal and the WHC negative terminal via a plurality of firstcomponent wires, wherein the plurality of first component wires includea first component wire length and a first component loop resistance; asecond component electrically connected to the first WHC positiveterminal and the first WHC negative terminal via a plurality of secondcomponent wires, wherein the plurality of second component wires includea second component wire length and a second component loop resistance;and wherein at least one of the first component wire length and thesecond component wire length are configured responsive to at least oneof the first component loop resistance and the second component loopresistance.
 2. The wire harness of claim 1, wherein the Wire HarnessConnector (WHC) further includes a second WHC positive terminal and asecond WHC negative terminal; a fifth component electrically connectedto the second WHC positive terminal and the second WHC negative terminalvia a plurality of fifth component wires, wherein the plurality of fifthcomponent wires include a fifth component wire length and a fifthcomponent loop resistance; a sixth component electrically connected tothe second WHC positive terminal and the second WHC negative terminalvia a plurality of sixth component wires, wherein the plurality of sixthcomponent wires include a sixth component wire length and a sixthcomponent loop resistance; and wherein at least one of the fifthcomponent wire length and the sixth component wire length are configuredresponsive to at least one of the fifth component loop resistance andthe sixth component loop resistance.
 3. The wire harness of claim 1,wherein the Wire Harness Connector (WHC) further includes a thirdcomponent electrically connected to the WHC positive terminal and theWHC negative terminal via a plurality of third component wires, whereinthe plurality of third component wires include a third component wirelength and a third component loop resistance; a fourth componentelectrically connected to the WHC positive terminal and the WHC negativeterminal via a plurality of fourth component wires, wherein theplurality of fourth component wires include a fourth component wirelength and a fourth component loop resistance; and wherein at least oneof the third component wire length and the fourth component wire lengthare configured responsive to at least one of the third component loopresistance and the fourth component loop resistance.
 4. The wire harnessof claim 2, wherein the Wire Harness Connector (WHC) further includes aseventh component electrically connected to the second WHC positiveterminal and the second WHC negative terminal via a plurality of seventhcomponent wires, wherein the plurality of seventh component wiresinclude a seventh component wire length and a seventh component loopresistance; an eighth component electrically connected to the second WHCpositive terminal and the second WHC negative terminal via a pluralityof eighth component wires, wherein the plurality of eighth componentwires include an eighth component wire length and an eighth componentloop resistance; and wherein at least one of the seventh component wirelength and the eighth component wire length are configured responsive toat least one of the seventh component loop resistance and the eighthcomponent loop resistance.
 5. The wire harness of claim 1, wherein theplurality of first component wires includes at least one first componentpositive wire having a first component positive wire resistance and afirst component positive wire length and at least one first componentnegative wire having a first component negative wire resistance and afirst component negative wire length, wherein the first component loopresistance includes the first component positive wire resistance and thefirst component negative wire resistance; the plurality of secondcomponent wires includes at least one second component positive wirehaving a second component positive wire resistance and a secondcomponent positive wire length and at least one second componentnegative wire having a second component negative wire resistance and asecond component negative wire length, wherein the second component loopresistance includes the second component positive wire resistance andthe second component negative wire resistance.
 6. The wire harness ofclaim 5, wherein the plurality of third component wires includes atleast one third component positive wire having a third componentpositive wire resistance and a third component positive wire length andat least one third component negative wire having a third componentnegative wire resistance and a third component negative wire length,wherein the third component loop resistance includes the third componentpositive wire resistance and the third component negative wireresistance; the plurality of fourth component wires includes at leastone fourth component positive wire having a fourth component positivewire resistance and a fourth component positive wire length and at leastone fourth component negative wire having a fourth component negativewire resistance and a fourth component negative wire length, wherein thefourth component loop resistance includes the fourth component positivewire resistance and the fourth component negative wire resistance. 7.The wire harness of claim 4, wherein the plurality of fifth componentwires includes at least one fifth component positive wire having a fifthcomponent positive wire resistance and a fifth component positive wirelength and at least one fifth component negative wire having a fifthcomponent negative wire resistance and a fifth component negative wirelength, wherein the fifth component loop resistance includes the fifthcomponent positive wire resistance and the fifth component negative wireresistance; the plurality of sixth component wires includes at least onesixth component positive wire having a sixth component positive wireresistance and a sixth component positive wire length and at least onesixth component negative wire having a sixth component negative wireresistance and a sixth component negative wire length, wherein the sixthcomponent loop resistance includes the sixth component positive wireresistance and the sixth component negative wire resistance.
 8. The wireharness of claim 7, wherein the plurality of seventh component wiresincludes at least one seventh component positive wire having a seventhcomponent positive wire resistance and a seventh component positive wirelength and at least one seventh component negative wire having a seventhcomponent negative wire resistance and a seventh component negative wirelength, wherein the seventh component loop resistance includes theseventh component positive wire resistance and the seventh componentnegative wire resistance; the plurality of eighth component wiresincludes at least one eighth component positive wire having an eighthcomponent positive wire resistance and an eighth component positive wirelength and at least one eighth component negative wire having an eighthcomponent negative wire resistance and an eighth component negative wirelength, wherein the eighth component loop resistance includes the eighthcomponent positive wire resistance and the eighth component negativewire resistance.
 9. The wire harness of claim 5, wherein at least one ofthe first component positive wire length, first component negative wirelength, second component positive wire length and second componentnegative wire length are configured responsive to at least one of thefirst component loop resistance and the second component loopresistance.
 10. The wire harness of claim 6, wherein at least one of thethird component positive wire length, third component negative wirelength, fourth component positive wire length and fourth componentnegative wire length are configured responsive to at least one of thefirst component loop resistance, the second component loop resistance,the third component loop resistance and the fourth component loopresistance.
 11. The wire harness of claim 7, wherein at least one of thefifth component positive wire length, fifth component negative wirelength, sixth component positive wire length and sixth componentnegative wire length are configured responsive to at least one of thefifth component loop resistance and the sixth component loop resistance.12. The wire harness of claim 8, wherein at least one of the seventhcomponent positive wire length, seventh component negative wire length,eighth component positive wire length and eighth component negative wirelength are configured responsive to at least one of the fifth componentloop resistance, the sixth component loop resistance, the seventhcomponent loop resistance and the eighth component loop resistance. 13.The wire harness of claim 5, wherein the first component loop resistanceand the second component loop resistance are balanced when the firstcomponent loop resistance and the second component loop resistance aresubstantially equal.
 14. The wire harness of claim 6, wherein the firstcomponent loop resistance, the second component loop resistance, thethird component loop resistance and the fourth component loop resistanceare balanced when the first component loop resistance, the secondcomponent loop resistance, the third component loop resistance and thefourth component loop resistance are substantially equal.
 15. The wireharness of claim 7, wherein the fifth component loop resistance and thesixth component loop resistance are balanced when the fifth componentloop resistance and the sixth component loop resistance aresubstantially equal.
 16. The wire harness of claim 8, wherein the fifthcomponent loop resistance, the sixth component loop resistance, theseventh component loop resistance and the eighth component loopresistance are balanced when the fifth component loop resistance, thesixth component loop resistance, the seventh component loop resistanceand the eighth component loop resistance are substantially equal. 17.The wire harness of claim 1, wherein at least one of the first componentand the second component is a thermocouple.
 18. A method forelectrically balancing a wire harness electrically connected with afirst component and a second component, wherein the wire harnessincludes a Wire Harness Connector (WHC) having a WHC positive terminaland a WHC negative terminal, wherein the first component is electricallyconnected to the WHC positive terminal and the WHC negative terminal viaa plurality of first component wires, wherein the plurality of firstcomponent wires include a first component wire length and a firstcomponent loop resistance and wherein the second component electricallyconnected to the first WHC positive terminal and the first WHC negativeterminal via a plurality of second component wires, wherein theplurality of second component wires include a second component wirelength and a second component loop resistance, the method comprising:determining the first component loop resistance; determining the secondcomponent loop resistance; and configuring at least one of the firstcomponent wire length and the second component wire length to balancethe resistance of the wire harness.
 19. The method of claim 18, whereinconfiguring at least one of the first component wire length and thesecond component wire length to balance the resistance of the wireharness includes, configuring at least one of the plurality of firstcomponent wires and the plurality of second component wires to cause thefirst component loop resistance and the second component loop resistanceto be substantially equal.
 20. The method of claim 18, whereinconfiguring at least one of the first component wire length and thesecond component wire length to balance the resistance of the wireharness includes configuring at least one of the first component wirelength and the second component wire length to cause the first componentloop resistance and the second component loop resistance to besubstantially equal.